Learning A's and B's
The exercises reproduce elements of technically correct running within the energy system fatigue of running itself. The fatigue experienced is neuromuscular. In terminology often used in Europe, these exercises are referred to as ‘second derivative’ exercises. This refers to the exercises being two steps removed from the actual motion desired and used to break down and rehearse elements of the desired motion.
The two basic exercises are called “A’s” and “B’s”. The progression starts with the “A” exercises (high knee lift) using one leg only. The actions to be stressed are the high knee left (lifting the thigh forwards not the heel backwards), tall hips (tight stomach and back), stretched body position, cocked ankle (toe up, heel up), arms aligned as in running and an active landing on the ball of the foot (pull-push backward motion).
Once an athlete is able to do this correctly with one leg, he/she should try the other leg with the coach watching closely for differences from on leg to the other. Any such difference is important to observe and analyze at the outset. When each leg is able to do the action correctly, the athlete may begin to “march” using both legs alternately.
There is a three-fold progression: (1) marching, (2) skipping, (3) running. Each stage must be mastered before the next is attempted. Too early a progression will quickly result in difficulty wit the next stage.
“B” exercises (high knee lift with lower leg extension) follow the same learning sequence. Combinations of A’s and B’s can also be done, even with each leg doing a different exercise. There is a slight movement forward during the execution of these exercises of 5 foot-contacts per meter. As a skill exercise, distances of between 10-20 meters are sufficient. Over longer distances, the exercises are extremely useful in training the strength endurance component for athletes in a wide variety of events and sports.
Exercises can be done in two forms, each reflecting varying durations and intensities. In the Power Speed form, exercises are done for less than 10 seconds, for less than 10 repetitions, or for less than 20 meters. The rhythm is quick, making this a usual activity in the Warm-Up. In the Strength Endurance form, the exercises are done for more than 10 seconds, for more than 10 repetitions or for more than 20 meters. The rhythm is slower. There is no upper limit on the duration and quantity of strength endurance exercises, even up to 150 meters or more. The limiting factor is the ability to maintain perfect technique. Strength Endurance exercises follow a workout and are never done in a warm-up because of the likelihood of accumulating fatigue.
For more information on speed and similar articles, “The Sciences of SAC” by Brent McFarlane